SERS Sensing of Food Colourants

Food colourants (synthetic or natural) are added to food and drinks to increase their visual attractiveness to consumers and to restore their original appearance when it 

Sudan 1 dye was extracted from chilli powder and detected using Au NPs in concentration as low as 48 ng in 1 g of powder (Cheung et al. 2010). Recently, Jahn and co-workers employed enzymatically generated Ag NPs prepared by a bottom-up and self-organizing procedure (see Sect. 3.4.2.1), in combination with a lipophilic sensor layer for the detection of water-insoluble azo-dye Sudan III in real food matrix, paprika products (Jahn et al. 2015). The surface modification consisted of self-assembled aliphatic hydrocarbons with a thiol moiety forming hydrophobic monolayer on the SERS substrate. The resulting layer repelled unwanted water-soluble analytes from the surface whereas water-insoluble ones were adsorbed and detected by SERS. The riboflavin was introduced as a water-soluble competitor, which is part of the relevant food matrices. Sudan 111 dye was detected down to 9 pmol 1 concentration from paprika powder extract in the methanol. Beside this, lipophilic sensor layer can also be applied for further analytical tasks for which it is beneficial to discriminate water-soluble from insoluble substances. 

Sweet drinks with high levels of complexity 

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